Vascular smooth muscle cells are responsible for producing the bulk of the connective tissue proteins in major arteries and have been implicated in the pathogenesis of atheriosclerosis as the cell responsible for connective tissue proliferation. Previous studies have shown that these smooth muscle cells in culture are capable of synthesizing elastin, Type I, Type III and basement membrane collagen, and glycosaminoglycans. Recently we have found that estradiol treatment of these cells in culture causes a significant reduction in the quanitity of procollagen Type III produced by these cells. To further elucidate the mechanism of the estradiol effect, we plan to monitor three components of collagent produced in the cell culture: the intracellular soluble prococllagens, the extracellular soluble collagens in the medium and the extracellular insoluble collagen incorporated into the matrix. Distributions of the various collagen types in each of these compartments will be assessed. Collagen mRNA will be monitored by employing cell-free translation system previously used in our laboratory. After preparation of cDNA clones for the individual collagen chains, we will quantify the levels of collagen mRNA and examine collagen gene structure and expression. Collagen typing in the various collagen components and determination of the level of collagen mRNA and gene expression will be determined as a function of hormone treatment as well as cell density.